Method of making iridium-tipped metallic rods



(No Model.)

s. W SKINNER & W. M. THOMAS;

METHOD OF MAKING IRIDIUM TIPPED METALLIC RODS. No. 250,590.

Patented 1360.6,1881

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\ l l i UNITED STATES PATENT OFFICE.

SAMUEL W. SKINNER AND WILLIAM M. THOMAS, OF CINCINNATI, OHIO.

METHOD OF MAKING IRIDIUM-TIPPED METALLIC RODS.

SPECIFICATION forming part of Letters'Patent No. 250,590, dated December 6, 1881.

Application filed July 21, 1881. (No model.)

To all whom it may concern Be it known that we, SAMUEL W. SKINNER and WILLIAM M. THoMAs,both of Cincinnati, in the county of Hamilton and State of Ohio, have invented a new and useful Method of Making Iridium-Tipped Metallicltods, ofwhich the following is a specification.

Our invention relates to a new and useful manufacture of iridium tipped metallic rods for use as electrodes in the production of electric illumination, and for otherpurposes, by th e electro -fusion of granular iridium or iridosmium (iridosmine) upon a rod of copper or other suitable metal.

In the accompanying drawings, Figure 1 represents a carbon positive electrode whose cup-shaped pole is charged with granulated iridium, and associated with such positive electrode a negative electrode of copper. Fig. 2 shows the copper stem or rod of the said negative electrode tipped with iridium transferred from the positive electrode. Fig. 3 shows the same electrodes with current reversed for the purpose of fusing the iridium tip and the copper stem integrally together. Fig. 4 shows the two electrodes reversed in position and the current restored to its original direction. Fig. 5 shows amodification of our method ofjointfusion, in which theline of contactof the iridium tip and the copper rod is brought in the path of an electric are between two ordinary electrodes, the copper rod itself not being in the path of the electriccurrent. Fig. 6 shows our iridiumtipped rod placed in a mold for the purpose of casting about the rod proper or stem a re-enforce of the same or some other metal than that which composes said stem, so as to produce the modification of our invention shown in Fig. 7. Figs. 8 to 11, inclusive, represent successive stages in the manufacture of a modification of our invention. In these figures, Fig. 8 has its lower electrode cupformed and positive and charged with granulated iridium or iridosmium. Fig. Qrepresents the same electrodes with the iridium tip formed upon the negative electrode by electrofusion and aggregation. Fig. 10 shows the iridium tip broken off of the negative electrode and placed in a mold for casting a copper or other suitable metallic stem. Fig. 11

represents our iridium -tipped rod formed by the successive operations shown in Figs. 8, 9, and 10.

For the manufacture of our said iridiumtipped rod we provide an electrode, A, of gasretort carbon or its equivalent. This electrode has formed in its free extremity or pole a cavity, a, which cavity is presented upward and is charged with a quantity of iridium, O, (or one of the native alloys of that metal, such as lll(lOSl'l1llll11,) preferably in the granulated form. We further provide an electrode, B, of copper or other suitable refractory metal of good electrical conductivity, whose pole is presented in suitable proximity to that of electrode A. These electrodes having been so connected with a dynamo-magnetic machine or other source of electricity as to direct the positive current to A, and the poles having been sufficiently approximated to evolve an electric arc, and retained in that position until the surface ot the iridium has become suffieiently fused and the tip of the negative electrode B has become suiiiciently softened by heat, the poles are brought into momentary contact, so as to cause a portion of the molten or semi-molten iridium to adhere to the soft ened tip of the negative B. This process is repeated until there adheres to the negative B a compact nodule or mass, U, of iridium of the desired dimensions. The said pole-contacts being made and broken quickly, and with a sensible interval of time between the contacts, secure the double advantage of intimate incorporation of the electrode-stem B With its iridium tip 0 by molecular interfusion at their plane of junction with an external lamina of pure and therefore highly refractory iridium. Instead, however, of thus tipping the negative electrode, we sometimes place the rod to be tipped out of the path of the electric current, merely heating up its tip in the electric are formed by proximity with such an iridium-filled positive with an ordinary carbon negative, the tip of the rod being applied as often as may be necessary to take up the granules of iridium.

For fixing and incorporating the iridium tip with its copper stem the plane ofjunction thereof is brought under the momentary action of the are, either, as in Fig. 3, by reversing the current and directing the arc to said junction, or, as in Fig. 5, by placing the tipped rod with its plane of junction in contact with an are between any pair of electrodes. Vith either mode the rod is during contact briskly rotated upon its axis to prevent excessive fusion. The effect under either mode is to create an alloy of the materials of B and O at their plane of junction, and to intimately incorporate them in one continuous and integral mass.

When to be employed for illuminative purposes the thus-formed iridium tipped rod is used as the negative electrode, in association with a positive, A, oi gas-retort carbon or equivalent substance, as shown in Fig. 4, and in such arrangement the thus-formed negative electrode,being practicallyindestructible, may be a fixture. The point of light will thus remain in one place with corresponding steadiness of illumination.

A modification of our said iridium -tipped rod is produced by placing it in a mold, as shown in Fig. 6, and pouring metal around the stem, either of the same kind or difi'erent. For example, the stem proper or core being of platinum or steel, the re-euforce or envelope E may be of copper.

The mold may be of any desired construction. \Ve have used and prefer such an an rangement as shown in Fig. 6, in which the tip is nearly buried in a sand bed, 1), and the re-cni'orce metal is received in a tube, F, of the desired caliber, which surrounds the stem. Such reenforced iridium-tipped rod is shown at Fi g. 7, a portion ofthe re en force being broken away, so as to expose the core.

Still a dii'i'erent mode of manufacturing our iridium -tipped metallic rod is shown in Figs. 8 to 11,iuclusive,in which a carbon negative B, is employed, as shown in Fig. 8, and from which the iridium tip .0, after accumulation upon the carbon, as shown in Fig. 9, is broken off and buried in a sand bed, D, from which only a small portion protrudes, which portion being inclosed in a tube, 1?, molten copper is poured into the same,so as to form an iridiumtipped metallic rod, E C, as shown in Fig. 11, a portion of the stem E in said figure being removed to show the connection of tip and stem.

An iridium -1ipped rod mamii'actured as above possesses several very important advantages. Its pole being absolutely pure and free from phosphorus and other impuritics,its electrical conductivity is superior to any other known electrode of sufilcient durability. The purity, density, and homogeneousness of the iridium tip, and its close and intimate incorporation with the supporting rod or stem, secure a free escape of heat. A tip thus produced of pure iridium is both infusible and incombustible when used as a negative electrode. Such iridium tipped rods may be utilized by manufacture into tools for various mechanical purposes-such, for example, as writing-pens, gravers, scribes for glaziers and millstonedressers, dcntal instruments, needle-drills, 86C.

The right is reserved to make one or more such manufactures the subjects of separate applications for patent.

Ve are aware that it has been proposed to tip metallic rods with iridium by clectro-t'usion of the latter upon a bldck of copper; but we consider such means objectionable, because of the liability of alloying the iridium by contact with the fumes ot' the copper positive. \Ve therefore do not claim such process, broadly.

To claim as new and of our invention- 1. The process oi" manufacturing an iridiumtipped metallic rod, which consists in charging with granulated iridium a cup-formed carbon positive electrode and bringing the same, while under the action of galvanic discharge, into repeated contact with the tip of a rod of other metal, substantially as set forth.

2. The process of manufacturing an iridiumtipped metallic rod, which consists in charging with granulated iridium a cup'formed carbon positive electrode and bringingthe same, while under the action of galvanic discharge, into repeated contact with the tip of a rod of other metal, the rod proper being then enveloped with a re-cnforeeot' the same or diii'erent metal. substantially as set forth.

In testimony of which invention we hereunto set our hands.

SAHUEL W. SKINNER. \VILLIAM M. THOMAS.

Attcst:

G-Eo. H. KNIGHT, SAML. S. CARPENTER. 

